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| Home > Publications database > Processing and creep resistance of short SiC fiber containing Ti$_{3}$SiC$_{2}$ MAX phase composites |
| Book/Dissertation / PhD Thesis | FZJ-2021-03205 |
2021
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
ISBN: 978-3-95806-558-1
Please use a persistent id in citations: http://hdl.handle.net/2128/28714
Abstract: Alternative materials for high temperature applications might offer a solution to higherefficiency and low fuel consumption for jet engines. A possible candidate for such materialis Ti$_{3}$SiC$_{2}$ which is a ceramic material with unique combination of mechanical properties at high temperature. Ceramics are brittle in nature and have a typically low Weibull modulus as compared to metals. Hence, monolithic ceramic parts cannot directly replace metal parts due to the lack of reliability. Ceramic matrix composites (CMCs) with bulk ceramic material as the matrix and a ceramic fiber as the reinforcement offers the possibility to have high strength at high temperature but present some limitations like high costs and very few applications despite the huge economical efforts in the last decade. The complex processing routes followed for the fabrication of CMC have limited the applications. The present work is about the fabrication of a CMC with Ti$_{3}$SiC$_{2}$ as the matrix and short SiC fiber as the reinforcement material. Ti$_{3}$SiC$_{2}$ is a special ceramic material which is machinable at room temperature and has a certain degree of plasticity at high temperature(∼1200 °C). A novel molten salt-based process was developed to synthesize high purity Ti$_{3}$SiC$_{2}$ at a large scale (1kg/batch) in air. The method involved mixing of elemental precursor with KBr salt and high temperature treatment at 1250 °C to obtain the desired Ti$_{3}$SiC$_{2}$ phase. Al was added to the reaction mixture to enhance the purity of Ti$_{3}$SiC$_{2}$. The effect of different levels of Al addition on the evolution of the Ti$_{3}$SiC$_{2}$ phase was studied. The synthesis process itself was studied to understand the barrier of oxidation to the oxidation prone materials. Apart from Ti$_{3}$SiC$_{2}$, a wide range of non-oxide ceramicslike TiC, Ti$_{2}$AlC, Ti$_{3}$AlC$_{2}$, Cr$_{2}$AlC, Ti$_{2}$AlN, MoAlB and many more were synthesized for the proof of concept. Metals like titanium were also sintered in dense and porous forms using the same process in air. The method was referred to as Molten Salt Shielded Synthesis/Sintering (MS$^{3}$). MS$^{3}$ process resulted in a reduction of the synthesis temperature of Ti$_{3}$SiC$_{2}$ along with other non-oxide ceramics. MS$^{3}$ process can be carried out in air without the need of expensive atmosphere-controlled furnaces. The dissolution of salt after MS$^{3}$ process results in micro-metric agglomerated powder which does not need to be milled unlike conventional solid-state reactions. The synthesized Ti$_{3}$SiC$_{2}$ powder was sintered in spark plasma sintering (SPS) furnace at 1250 °C with a uniaxial pressure of 80 MPa. Similarly, CMCs were also sintered in SPS by following a powder metallurgical process to mix the reinforcement with the synthesized Ti$_{3}$SiC$_{2}$ powder. The reinforcement of Ti$_{3}$SiC$_{2}$ was done in macroscale and microscale. The macroscale reinforcement was done by adding 10 and 20 vol.% chopped polycrystalline SiC fibers (1 mm) whereas the microscale reinforcement was done by adding 10and 20 vol.% of single crystalline SiC whiskers.[...]
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